1. Field of the Disclosure
The disclosure relates to a composition for an organic hard mask and a method for forming a pattern of a semiconductor device using the same. More specifically, the disclosure relates to a composition for a organic hard mask containing a polyamic acid compound on an underlying layer and to a method for forming a pattern used in a manufacturing process of all semiconductor devices by coating a organic hard mask film, and depositing a second hard mask film with a silicon nitride (SiON) film thereon to form a double hard mask film having excellent etching selectivity, when a uniform photoresist pattern is formed.
2. Description of the Related Technology
Due to development in the manufacturing technology of semiconductor devices and expansion of application fields of memory devices, a method for manufacturing a high capacity memory device having a highly developed degree of integration has been required. A lithography process has been widely used in a line pattern formation process for gate and bit line or a contact hole pattern formation process for bit line contact.
The lithography process has been improved to form a critical dimension (CD) below 0.07μ with a light source of short wavelength such as deep ultra violet (DUV) rays of chemical amplification instead of a light source of long wavelength such as I-line or KrF (248 nm).
Meanwhile, it is necessary to improve chemically amplified photoresist having high resolution to ArF (193 nm) or VUV (157 nm) as DUV light sources in the lithography process.
Since a chemically amplified photoresist has a lower etch resistance to etching gases than that of underlying layers (such as metal layers, for example) it is impossible to obtain a stable etching selectivity when a photoresist film is formed at 100 nm and less on the underlying layer to form a metal pattern of high integration. As a result, it is difficult to form a uniform pattern.
In order to form a uniform pattern, an organic film using amorphous carbon and an inorganic film using SiON are formed between an underlying layer and a photoresist film, and then an etching process is performed with the films as a hard mask film. Since the amorphous carbon has a physical property like organic materials but is not changed at high temperature of 400° C., the inorganic film can be stably formed thereon. The hard mask film is easily removed after the etching process.
FIGS. 1a through 1c illustrate a conventional method for forming a pattern by using amorphous carbon.
Referring to FIG. 1a, an amorphous carbon layer 3, a SiON film 5, a bottom anti-reflection film 7 and a photoresist film 9 are sequentially formed on an underlying layer 1.
The amorphous carbon layer is formed at a thickness ranging from 200 nm to 700 nm by a CDD method, and the SiON film is formed at a thickness ranging from 30 nm to 100 nm with carbon CVD equipment (produced by AMAT Co.).
A lithography process is performed on the photoresist film 9 to form a photoresist pattern 9-1. Then, an etching process is performed on the amorphous carbon layer 3, the SiON film 5, and the antireflection film 7 with the photoresist pattern 9-1 as an etching mask to obtain a deposition pattern comprising an amorphous carbon layer pattern 3-1, a SiON film pattern 5-1 and an antireflection film pattern 7-1 as shown in FIG. 1b. 
Thereafter, the underlying layer 1 is etched with the deposition pattern of FIG. 1b as an etching mask, and developed to obtain an underlying layer pattern 1-1 as shown in FIG. 1c. 
However, in the above-described process, additional deposition equipment and new amorphous carbon gas materials are required to form the amorphous carbon layer 3. As a result, the process cost is increased, and the process step becomes complicated.